Possible Clues:

• It could be the death of you to have one in a broken spoon
• One in the spoon, 21 down, will make one 14 down
• The last thing you'd take is one of this in a spoon
• One of this in a spoon might be the death of you
• If taken, it can harm or kill
• Even one such in a spoon is enough to do you in
• In the spoon there's one that won't do you any good
• I spoon up the lethal substance
• Kind of pen
• Damaging stuff - drink?